Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
  • C21D8/0236—Cold rolling
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
  • C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
  • C21D8/0436—Cold rolling
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/003—Apparatus
  • C23C2/0038—Apparatus characterised by the pre-treatment chambers located immediately upstream of the bath or occurring locally before the dipping process
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
  • C23C2/022—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating
  • C23C2/0224—Two or more thermal pretreatments
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
  • C23C2/06—Zinc or cadmium or alloys based thereon
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
  • C21D8/0226—Hot rolling
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
  • C21D8/0447—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment
  • C21D8/0473—Final recrystallisation annealing

Definitions

• the present invention relates to a cold-rolled steel sheet, a hot-dip galvanized steel sheet, and a method for producing the same, which are used for automobiles, home appliances, building materials, and the like. It is about how to obtain. Background art
• ultra-low carbon steel sheet As a steel sheet for use in automobiles and the like, ultra-low carbon steel sheet is widely used because of its excellent additivity (see Japanese Patent Application Laid-Open No. 58-185752).
• JP-A-3-130323, JP-A-4-143228, and JP-A-1-161624 disclose that C, Mn, It is disclosed that excellent workability can be obtained by reducing the amount of P and the like as much as possible.
• the effect of the present invention is similarly exerted in a good workability high-strength cold-rolled steel sheet reinforced with P or Si.
• the technologies relating to these steel sheets are represented by JP-A-59-31827, JP-A-59-38337, JP-B-57-57945, and JP-A-61-276931.
• no attempt is made to improve the yield at the ends of the coil in the width and longitudinal directions, and Ti, Nb carbosulfide as in the present invention is actively utilized. Not a technology.
• the present invention solves the above-mentioned problems, and provides a cold-rolled steel sheet excellent in uniformity of workability with extremely little material deterioration in the width and longitudinal end portions of the coil, and a method for manufacturing the same.
• the present inventors have conducted intensive studies to obtain a cold-rolled steel sheet having excellent properties as described above.As a result, the present inventors have found that carbosulfides are actively precipitated in the hot rolling process and the amount of solute C is reduced as much as possible. Was determined to be extremely important.
• the amount of S precipitated as MnS is minimized by restricting the amount of ⁇ in order to actively use the contained S, and the Nb-containing carbon sulfide is
• carbides such as carbonaceous sulfides, Ti-containing carbosulfides or Nb-Ti-containing carbosulfides are positively precipitated to reduce solid solution C before winding.
• a large amount of solute C is present at the end of the coil because solid solution C is sufficiently fixed before winding. Deterioration of the material due to remaining in the steel or precipitation of fine carbides is reduced.
• the reduction in the amount of solid solution C before winding reduces the variation in the material inside the coil and reduces the dependency on the winding temperature.
• an ultra-low carbon steel with a carbon content of 0.0005 to 0.007% by weight with Nb or Nb-Ti added In the steel, 0.004 to 0.02% by weight of S and 0.01 to 0.15% by weight of Mn are added, and when Nb or Nb-Ti is added, after coil winding after hot rolling , Between the contained S and the S that precipitates as Mn S
• the gist of the present invention is as follows. Below% is all heavy S%.
• the steel having the above components is subjected to hot rolling at a heating temperature ⁇ 1250 ° C and a finishing temperature ⁇ (Ar a — 100) ° C, and is wound at a temperature range from room temperature to 800 ° C. It is characterized by performing cold rolling and further annealing at a temperature higher than the recrystallization temperature, or, after performing the cold rolling, passing through a continuous molten zinc plating line to form an annealing furnace in the line.
• This is a method for producing a cold-rolled steel sheet or a cold-rolled hot-dip galvanized steel sheet, characterized by annealing at a recrystallization temperature or higher, applying zinc plating during a cooling process, and performing alloying treatment as necessary.
• Fig. 1 (1) shows the relationship between the coil winding temperature dependence of the r value and the K value when Nb was added alone
• Fig. 2 (2) shows the coil winding temperature dependence of the r value and the L value.
• FIG. 2 (1) shows the relationship between the coil winding temperature dependence of the r value and the K value in the case of adding Ti-Nb composite
• Fig. 2 (2) shows the dependence of the r value on the coil winding temperature.
• FIG. 4 is a diagram showing a relationship between the value and the L value.
• Fig. 3 (1) shows the relationship between the coil winding temperature dependence of the r value and the K value when Ti alone is added
• Fig. 2 (2) shows the dependence of the r value on the coil winding temperature. It is a figure which shows the relationship of Ti * ZS value.
• FIG. 4 is a graph showing a relationship between r and r when Nb alone is added and when Nb—Ti composite is added.
• the amounts of S, Mn, Nb, Ti, etc. are specified as elements to be added to the ultra-low carbon steel, a specific carbonitride is sufficiently precipitated and solidified in the coil before winding.
• a specific carbonitride is sufficiently precipitated and solidified in the coil before winding.
• C is set to 0.007% or less, but is preferably set to 0.003% or less.
• the lower limit is 0.0005% from the viewpoint of vacuum degassing cost.
• Si Since Si is effective as an inexpensive element for strengthening, it is used according to the desired strength level. However, if the Si content exceeds 0.8%, the YP sharply increases, the elongation decreases, and the plating property is significantly impaired.
• the content is preferably 0.3% or less from the viewpoint of plating properties. Unless high strength (350MPa or more in TS) is required, 0.1% or less is more preferable. The lower limit is 0.005% from the viewpoint of steelmaking costs.
• Mn is one of the very important elements in the present invention.
• Mn is preferably 0.15% or less, and more preferably less than 0.10%.
• the lower limit is set to 0.01%.
• P is actively used as an inexpensive high-strength element in the same way as Si, depending on the desired strength level.
• the P content exceeds 0.2%, it causes cracks during hot or cold working, significantly deteriorates the secondary workability, and significantly slows down the alloying speed of the molten zinc plating, so that 0.2% or less.
• the content is more preferably 0.08% or less. If high strength is not required, 0.03% or less is more preferable.
• S is an extremely important element in the present invention, and the amount of S is set to 0.004 to 0.02%. If the S content is less than 0.004%, the amount of Nb and other carbosulfides deposited will not be sufficient, not only when winding at low temperatures, but also at the coil ends even if winding at high temperatures. In large amounts, fine grain precipitation of NbC impairs the grain growth during annealing and significantly deteriorates workability. If the S content exceeds 0.02%, hot cracking is liable to occur, and the same problem occurs because MnS precipitates more than the precipitation of carbosulfides such as Nb, so that uniformity of workability is not ensured. In addition, 0.004 to 0.012% is a more preferable range.
• A1 needs to be added at least 0.005% as a deoxidizer.
• N like C, increases the amount of Al, which is a nitride-forming element, with the increase in the cost, and increases the cost.
• N is set to 0.007% or less. It is preferably 0.003% or less.
• Nb is the most important element in the present invention, and precipitates as Nb-containing carbosulfide (for example, Nb 4 C 2 S 2 ), and also refines the hot-rolled sheet to improve deep drawability. Also, when Nb alone is added, the anisotropy ⁇ r of the r value is as extremely small as 0.2 or less, and when the molten zinc plating is applied, the powdering resistance is remarkably improved. Therefore, when Nb is added alone, it is added in the range of 0.005 to 0.1%. If Nb is less than 0.005%, Nb-containing carbosulfide cannot be precipitated before winding, and adding more than 0.1% not only saturates the effect of fixing C but also significantly reduces ductility. You. From the above viewpoints, Nb is more preferably in the range of 0.02 to 0.05%.
• Ti When Ti is added alone, it is added in the range of 0.01 to 0.1%. If the Ti content is less than 0.01%, the Ti-containing carbosulfide ThC 2 S 2 cannot be precipitated before winding, and the effect of fixing C is saturated even if an amount exceeding 0.1% is added. In addition, it becomes difficult to ensure the release resistance of the plating layer during press molding. From the viewpoint of sufficiently precipitating Ti 4 C 2 S 2 , it is preferable to add the Ti content in excess of 0.025%.
• Ti * NO S is preferably more than 2, and more preferably 3 or more if further effect is desired.
• Nb and Ti are less than the above lower limits, the Nb-Ti-containing carbosulfide cannot be precipitated before coil winding.
• the amounts of Nb and Ti each exceed 0.05%, not only does the effect of fixing C saturate, but also the ductility of Nb is significantly deteriorated, and the release resistance of the stick layer during press forming is significantly reduced with Ti. It is difficult to secure.
• the Ti content is more preferably set to 0.05% or less.
• the L value must be 0.7 or more in the case of Nb-added steel or Nb-Ti composite added steel.
• the r value was taken as one of the workability properties, and the relationship between the variation of the r value at the winding temperature and the K value and L value was examined. Indicated.
• Fig. 1 shows an example of ultra-low carbon steel with Nb added alone.
• the steel components shown in Tables 1 and 2 are used, the K value and L value (average value) of each steel type are plotted on the horizontal axis, and the winding temperature of each steel type shown in Table 3 is shown.
• the difference between the r value at the highest temperature (r (high CT)) and the r value at the lowest temperature (r (low CT)) divided by the difference in the winding temperature is multiplied by 100, and this value is plotted on the vertical axis. I took it.
• Fig. 2 shows the results in Tables 11 and 12 using the chemical components in Tables 9 and 10.
• FIG. 3 illustrates the results of Tables 20 to 30 using the chemical components shown in Tables 17 to 19.
• the Nb-containing or Ti-Nb-containing carbosulfide basically has a force atomic ratio of 1 ⁇ NbZ S ⁇ 2, 1 ⁇ in which some of the Ti positions in Ti 4C2S2 are replaced with Nb.
• a composition ratio in the range of Nb / C ⁇ 2 for example, Nb 2 S 2
• the amount of C precipitated as carbide having a diameter of 10 nm or less is desirably 0.0001% or less, and the amount of C precipitated as carbide having a diameter of 20 nm or less is 0.0002% or less.
• B strengthens grain boundaries and improves secondary workability
• 0.0001 to 0.0030% is added as a component of the steel of the present invention as necessary. If less than 0.0001% is added, the effect is poor. If more than 0.0030% is added, the effect is saturated and ductility is deteriorated.
• the raw material for obtaining the above components is not particularly limited, but in addition to the method of preparing the components using iron ore and a blast furnace and a converter, scrap may be used as a raw material, May be melted.
• scrap may contain elements such as Cu, Cr, Ni, Sn, Sb, Zn, Pb, and Mo.
• the means for producing the slab used in the present invention does not matter. That is, any material such as a slab manufactured from an ingot, a continuous structure slab, or a slab manufactured with a thin slab caster may be used. Further, a direct-coupling process (CC-DR) of continuous forging-direct rolling, in which hot rolling is performed immediately after the slab is manufactured, may be used.
• CC-DR direct-coupling process
• the obtained slab is usually heated, but the heating temperature should be 1250 ° C or less in the case of Ni or Nb / Ti combined addition steel in order to increase the precipitation of Ti and Nb-containing carbosulfide as much as possible. Required. In the case of Ti alone added pressure to increase the amount of precipitation of T and C 2 S 2, which is less mandatory 1200 ° C. From the above viewpoint, the temperature is preferably 1150 ° C or lower. The lower limit of the heating temperature is 1000 ° C from the viewpoint of securing the finishing temperature.
• the heated slab is sent to a hot rolling mill where the finishing temperature (Ar 3 — 10 0) Perform normal rolling in the range of ° C to 1 000 ° C.
• the finishing temperature Ar 3 — 10 0
• normal rolling in the range of ° C to 1 000 ° C.
• a rough bar with a finish thickness of 20 to 40 mm in rough rolling is rolled at a total rolling reduction of 60 to 95% in finish rolling to obtain a hot-rolled sheet with a minimum thickness of 3 to 6 mm.
• the present invention has a feature that workability can be ensured even at a low winding temperature. That is, in the present invention, the precipitation of C is sufficiently completed as Nb-containing carbosulfide during the process from hot rolling to cooling after hot rolling, and the material is formed even after high-temperature winding. Does not significantly improve, and the material of the coil end does not deteriorate even when the coil is wound at a low temperature. Therefore, winding may be performed at an appropriate temperature for the operation.
• a temperature of 800 ° C can be adopted on the high temperature side, and a room temperature can be adopted on the low temperature side. That is, the steel sheet of the present invention does not depend on the winding temperature.
• the reason for limiting the temperature to 800 ° C on the high-temperature side is that if the temperature exceeds 800 ° C, the crystal grains of the hot-rolled sheet become coarse, the oxide scale on the surface becomes thick, and the cost of pickling increases.
• the reason for setting the temperature to the room temperature on the low temperature side is that if the winding is performed at a temperature lower than the room temperature, the winding operation requires an excessive facility and has no particular effect.
• the winding temperature is high, the slightly dissolved solid C that precipitates as fine carbides or the compound of P precipitates, and the material tends to deteriorate rather. is there. Therefore, it is preferable to perform winding at a temperature of 650 ° C. or less in order to improve the material. To avoid the precipitation of these harmful compounds completely, wind at a temperature below 500 ° C. Furthermore, if it is necessary to reduce the time required to lower the temperature to around room temperature after winding, it is preferable to rapidly cool the hot-rolled steel strip and wind it at 100 ° C or less. Needless to say, such low-temperature winding can reduce manufacturing costs.
• the winding coil is supplied to a cold rolling mill.
• the rolling reduction of cold rolling should be 60% or more from the viewpoint of ensuring deep drawability.
• Rolling reduction The upper limit is set to 98% because the effect on the cold rolling mill is only large and the effect is not so large.
• the cold-rolled steel strip is sent to a continuous annealing furnace, where it is annealed at a temperature above the recrystallization temperature, that is, 700 to 900 seconds for 30 to 90 seconds to ensure workability.
• the strip When the cold rolled steel strip is subjected to zinc plating, the strip is passed through a continuous molten zinc plating line having a continuous annealing furnace, a cooling facility, and a plating tank.
• the steel strip is heated in a plating line annealing furnace so that the maximum temperature reaches a temperature range of 750 to 900 ° C.
• the steel strip is heated to 420 to 500 ° from the viewpoint of plating properties and plating adhesion. It is immersed in a zinc plating tank in the temperature range of C and plated.
• the film is sent to a heating furnace for alloying of the plating film, and is alloyed for 1 to 30 seconds in a temperature range of 400 to 600 ° C. If the temperature is lower than 400 ° C, the alloying reaction is too slow to impair the productivity, and the corrosion resistance and weldability are deteriorated. If the temperature exceeds 600 ° C, the adhesion resistance is deteriorated. In order to obtain a plating layer having better adhesion, alloying is preferably performed in the range of 480 to 550 ° C.
• the heating rate in the continuous annealing or the continuous molten zinc plating line is not particularly limited, and may be a normal rate or an ultra-rapid heating of 1,000 ° C. Zs or more.
• Nb added with the chemical components shown in Tables 1 and 2 (continuation of Table 1) Tapping low-carbon steel in a converter, turning it into a slab with a continuous forming machine, heating it to 1140 ° C, hot rolling to a finishing temperature of 925, and a sheet thickness of 4.0 went.
• the average cooling rate at the run our table is about 30 ° CZs, and then the various winding temperatures as shown in Tables 3 and 4 (continuation of Table 3). And wound on a coil.
• a sample was cut out from the center of the hot rolled coil in the longitudinal direction, and the following processing was performed. That is, cold rolling was performed to 0.8 mm after pickling in the laboratory, and heat treatment equivalent to continuous annealing was performed.
• the annealing conditions are as follows: Annealing temperature: (shown in Tables 3 and 4), Soaking: 60 s, Cooling rate: Approx. 5 ° C / s from annealing temperature to 680 ° C, 680 ° C to room temperature It was about 65 ° CZ s.
• temper rolling was performed at a rolling reduction of 0.7% and subjected to a tensile test.
• the tensile test and the measurement of the average rank value (hereinafter referred to as r value) were performed using a JIS No. 5 test piece.
• the r value was evaluated at an elongation of 15%, and the values in the rolling direction (L direction), the direction perpendicular to the rolling direction (C direction), and the 45 ° direction (D direction) with respect to the rolling direction were measured. It was calculated by the following equation.
• the steels manufactured according to the scope of the present invention show excellent properties not only at the center of the coil but also at the end 10 m of the coil.
• the material deteriorated remarkably at the coil end, and in the case of low-temperature winding, the material deteriorated over the entire length of the coil. It is clear that this tendency becomes more pronounced at the end.
• the effects of hot rolling heating temperature on the material properties after cold rolling and annealing were investigated using steels C and Q (steel tapping slabs) in Tables 1 and 2.
• the slab was heated to 1100 to 1350 ° C on an actual machine, and hot-rolled so that the finishing temperature was 940 ° C and the sheet thickness was 4.0.
• the average cooling rate at the run-out table was about 40 ° CZs, and then the coil was wound at 620 ° C.
• the total length of the coil was about 200 m.
• a sample was cut out from the same coil from the same position as in Example 2, cold-rolled to 0.8 mm after pickling, and then subjected to a heat treatment equivalent to continuous annealing in a laboratory.
• the annealing conditions were as follows: annealing temperature: 810 ° C, soaking: 50 s, cooling rate: about 60 s to room temperature. After that, temper rolling was performed at a rolling reduction of 0.8%, and subjected to a tensile test.
• the steel manufactured according to the scope of the present invention is excellent not only in the central part of the hot-rolled coil but also in the ends thereof after cold rolling and annealing.
• the heating temperature was higher than 1250 ° C, the material after cold rolling and annealing was significantly deteriorated at the coil end.
• Hot rolling was performed using the steels B, D, G, J, L, N, R, and T in Tables 1 and 2 under the same conditions as in Example 1 (winding temperature: 730 ° C). Subsequently, it was pickled by an actual machine, cold rolled at a rolling reduction of 80%, and passed through an in-line annealing continuous molten zinc plating line. At this time, it was cooled after heating at the maximum heating temperature of 800 ° C, followed by conventional hot-dip zinc plating at 470 ° C (A1 concentration in the bath was 0.12%), and further heated at 560 ° C for about 12 seconds. Alloying treatment was performed. Further, passivation rolling of 0.8% was performed to evaluate the mechanical properties and the adhesion of the metal.
• the adhesiveness of the plating was determined by performing 180 ° close-contact bending to determine the peeling state of the zinc film from the amount of peeling that adhered to the tape after the adhesive tape was adhered to the bent part. did.
• the evaluation was based on the following five levels.
• the alloyed hot-dip zinc-plated steel sheet manufactured according to the scope of the present invention shows excellent characteristics regardless of the coil position.
• the workability varied greatly depending on the coil location.
• Ultra-low carbon steel containing Ti and Nb with the chemical components shown in Tables 9 and 10 (continued from Table 9) was tapped in a converter, turned into a slab by a continuous machine, and then heated to 1200 ° C. Then, hot rolling was performed so that the finishing temperature was 920 ° C and the plate thickness was 4. Omm.
• the average cooling rate in the run out table is about 40 ° C / s, and then the coils are wound at various winding temperatures as shown in Tables 3 and 4 (continued in Table 2). Wound up.
• a sample was cut out from the center of the hot-rolled coil in the longitudinal direction, and the following processing was performed. That is, cold rolling was performed to 0.8 garden after pickling in the laboratory, and heat treatment equivalent to continuous annealing was performed.
• the annealing conditions were as follows: annealing temperature: 810 ° C, soaking: 50 s, cooling rate: about 4 ° C Zs from the annealing temperature to 680 ° C, and about 70 ° CZs from 670 ° C to room temperature. After that, temper rolling was performed at a rolling reduction of 0.8% and subjected to a tensile test.
• the tensile test and the measurement of the average rank ford value (hereinafter referred to as r value) were performed using a J1S No. 5 test piece.
• the r value was evaluated at an elongation of 15%, and the values in the rolling direction (L direction), the direction perpendicular to the rolling direction (C direction), and the 45 ° direction (D direction) with respect to the rolling direction were measured. It was calculated by the equation.
• the steels produced according to the scope of the invention show excellent properties not only in the central part of the coil, but also at the end 10 m.
• the material deteriorated significantly at the coil end, and in the case of low-temperature winding, the material became poor over the entire length of the coil. It is clear that this tendency becomes more pronounced at the end.
• the effects of hot-rolling heating temperature on the material properties after cold rolling and annealing were investigated using steels B and K (tapping slabs) in Tables 9 and 10.
• the slab was heated to 1100 to 1350 ° C with an actual machine, and hot-rolled so that the finishing temperature was 940 ° C and the sheet thickness was 4. Omm.
• the average cooling rate in the run table was about 30 ° C / s, and the coil was then wound at 620 ° C.
• the total length of the coil was about 200 m.
• a sample was cut out of the same coil from the same position as in Example 2, cold-rolled until picking after pickling, and subjected to heat treatment equivalent to continuous annealing in a laboratory.
• the annealing conditions were as follows: annealing temperature: 790 ° C, soaking: 60 s, cooling rate: about 60 ° CZ s to room temperature. Then, temper rolling was performed at a rolling reduction of 0.8%, and subjected to a tensile test. The test results are summarized in Table 14.
• the steel manufactured according to the scope of the present invention is excellent not only in the center of the hot-rolled coil but also in the ends thereof after cold rolling and annealing.
• the heating temperature was higher than 1250 ° C, the material after cold rolling annealing at the coil end deteriorated remarkably.
• Hot rolling was performed using the steels A, E, G, I, L, M, Q, and T in Tables 9 and 10 under the same conditions as in Example 5 (winding temperature: 450 ° C). Subsequently, pickling was carried out using an actual machine, cold rolling was performed at a rolling reduction of 80%, and the sheet was passed through a continuous molten zinc plating line using an in-line annealing method. At this time, it is cooled after heating at the maximum heating temperature of 820 ° C, and the conventional molten zinc plating is performed at 470 ° C (A1 concentration in the bath is 0.12%). The alloying process was performed for 2 seconds. Furthermore, passivation rolling of 0.7% was performed to evaluate mechanical properties and plating adhesion. The results obtained are shown in Table 15.
• the adhesiveness of the plating was determined by performing 180 ° close-contact bending to determine the peeling state of the zinc film from the amount of peeling that adhered to the tape after the adhesive tape was adhered to the bent part. did.
• the evaluation was based on the following five levels.
• the alloyed hot-dip zinc-plated steel sheet manufactured according to the scope of the present invention shows excellent characteristics regardless of the position of the coil.
• the workability varied greatly depending on the coil location.
• the Nb content is low as in steel M, the plating adhesion is also deteriorated.
• Annealing conditions are shown in Table 20, Table 23 (continuation of Table 20—3), Table 26 (continuation of Table 20—6), and Table 29 (continuation of Table 20—9).
• Table 21 continuation of Table 20—1
• Table 24 continuation of Table 20—4
• Table 27 continuation of Table 20—7
• Table 30 continuation of Table 20—Table 20
• Temper rolling was performed at the reduction shown in 10) and subjected to a tensile test.
• the tensile test and the measurement of the average rank ford value (hereinafter referred to as r value) were performed using a JIS No. 5 test piece.
• the r value was evaluated at an elongation of 15%, and the values in the rolling direction (L direction), the direction perpendicular to the rolling direction (C direction), and the direction at 45 ° to the rolling direction (D direction) were measured. It was calculated by the equation.
• test results are summarized in Table 32 (continuation 1 in Table 31) and Table 34 (continuation 1-3 in Table 31).
• the steels manufactured according to the scope of the present invention show excellent properties not only at the center of the coil but also at the end 10 m.
• the material deteriorated remarkably toward the coil end, and in the case of low-temperature winding, the material deteriorated over the entire length of the coil. It is clear that this tendency becomes more pronounced at the end.
• the annealing conditions were as follows: annealing temperature: 790 ° C, soaking: 50 s, cooling rate: 60 ° CZs up to room temperature. Thereafter, temper rolling was performed at a rolling reduction of 1.0%, and subjected to a tensile test.
• the present invention is a.
• the steel manufactured according to the scope of the present invention is excellent not only at the center of the hot-rolled coil but also at the ends thereof after cold rolling annealing. .
• the heating temperature was higher than 1200 ° C, the material after cold rolling annealing at the coil end was significantly deteriorated.
• the adhesiveness of the plating was measured at 180 ° C, and the adhesion of the zinc film was measured by attaching an adhesive tape to the bent part and then peeling it off. It was judged from.
• the evaluation was based on the following five levels.
• the alloyed hot-dip galvanized steel sheet manufactured according to the scope of the present invention shows excellent properties regardless of the position of the coil.
• the coiling temperature after hot rolling can be reduced, and excellent materials can be obtained uniformly in the longitudinal and width directions of the coil.
• the coil end can be a product.
• the sheet thickness can be reduced, leading to an improvement in fuel efficiency, and a global environmental problem that has recently become a major problem. Its value is great because it can also contribute to problems.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Heat Treatment Of Sheet Steel (AREA)

Priority Applications (3)

Applications Claiming Priority (4)

Publications (1)

Family

ID=26374736

Family Applications (1)

Country Status (4)

Cited By (1)

Families Citing this family (23)

Citations (4)

Family Cites Families (9)

• 1995
  • 1995-12-28 WO PCT/JP1995/002768 patent/WO1996026300A1/ja not_active Application Discontinuation
  • 1995-12-28 EP EP95942317A patent/EP0767247A4/en not_active Withdrawn
  • 1995-12-28 US US08/737,107 patent/US5954896A/en not_active Expired - Fee Related
  • 1995-12-28 CN CN95192729A patent/CN1074054C/zh not_active Expired - Lifetime
• 2001
  • 2001-05-09 CN CN01117920.1A patent/CN1128241C/zh not_active Expired - Lifetime
  • 2001-05-09 CN CN01117921.XA patent/CN1128243C/zh not_active Expired - Lifetime

Patent Citations (4)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events